The Bell numbers

Known as: The Bell numbers

The number of partitions of a set with n members.

Named after the mathematician Eric Temple Bell.

The first 16 terms (starting from n=1) are:

1 1 2 5 15 52 203 877 4140 21147 115975 678570 4213597 27644437 190899322 1382958545

References

On-Line Encyclopedia of Integer Sequences